Injection and production flow rate regulating system for slimhole wells

ABSTRACT

A flow rate regulating system within an oil well with casing with a diameter less than or equal to 3½ inches, wherein the flow rate regulating system comprises: at least one regulating valve, for regulating flowrate, having a generally cylindrical body with a plurality of elongated grooves, a top sub in its upper portion and a sliding sleeve inside; and a regulating and calibrating shifting tool for regulating and calibrating the position of the sliding sleeve which has a generally cylindrical collet, a block set and a pair of nuts on each side of the block set.

FIELD OF THE INVENTION

The present invention refers to a system that allows regulating the flowrate of fluids to be selectively injected into slimhole oil wells withthe capability of measuring the injection flow rate distribution. Thesystem consists of a tubular body with through grooves and a slidingsleeve which restricts the flow through the grooves. The system allows agradual and variable regulation by using a shifting tool actuated fromthe surface by means of a Slickline or Wireline equipment, withoutaffecting the operating condition of the well, designed so as to providean inner diameter sufficient to introduce flow rate measurement tools.The required flow rate is defined according to the specific position ofthe sleeve and the groove geometry.

BACKGROUND OF THE INVENTION

The trend in the oil industry is heading towards small diameter orslimhole installations. This is a result of either lower drilling costsdue to reduced costs directly related to the rock volume to be extractedand to the diameter of the casing, as well as the use of less equipment,or to the necessity to recover injection wells with severe casingintegrity problems where re-tubing with 3½-inch (or less) GRER (GlassFiber Reinforced Epoxy Resins) or steel tubes is one of the mosteffective options.

Traditional selective injection systems used for secondary oil recoveryuse selective installations that allow injecting fluid into multiplelayers or reservoirs located at different depths in an oil well. Valvescomprising a calibrated orifice or choke are used to regulate the flowrate injected into each layer, so that the injection flow rate isregulated according to the diameter of the valve orifice and a springthat opens or closes the passage to keep the flow rate constant atdifferent injection pressures. These valves are placed inside mandrels,which are components used in traditional selective injection having thecharacteristic of employing a minimum inner diameter that allows the useof tools to place or remove valves and measure flow rates by means ofdifferent tools, but it also requires sufficient outer space to fit themandrel. Said space, existing between the tubing and the casing, andoccupied by the mandrel does not exist in slimhole conditions, thuspreventing the application of this technology.

In other cases, circulation valves with sliding sleeves are used. Saidsliding sleeves are devices used to communicate the interior of thetubing with the annular space existing between the casing and thetubing, said space allowing the fluid flow between them. These valvesoperate in three discrete positions, namely open, closed or equalized,and they do not allow gradual openings or closings in order to regulatethe flow rate therethrough.

Conventional selective injection systems, which use mandrels with valvesin casings with diameters equal to or greater than 5½ inches, areinstalled so that they inject into the different layers of the reservoirto be swept with fluid. Each mandrel and its valve is isolated from thefollowing one by mechanically or hydraulically sealing packers. Thesystems with sliding sleeves are operated by a shifting tool, which isactuated from the surface by means of a slickline or wireline equipment.

Although selective injection systems have been developed for tubedslimhole wells with 3½-inch casings, these allow injecting into alimited number of layers and do not allow measuring the flow ratedistribution thereto. Currently, there are no systems or devices in theglobal oil industry for slimhole selective injection for an unlimitednumber of layers.

A selective injection system known in the art is that disclosed inpatent AR 048661 B1, assigned to YPF S.A., which protects a slimholeselective installation system for injecting 3½-inch wells that uses adesign of integral regulating valves that are regulated at the surfaceand lowered to the point of interest by means of a pulling equipment,and in case of desiring to modify the regulation or replace a valve, itis necessary to remove the entire installation from the well. Thisimplies an intervention with pulling equipment, thereby resulting in avery expensive operation due to service costs and oil well downtime,which led to a very limited use.

U.S. Pat. No. 8,141,648 B2, assigned to Petroquip Energy Services,discloses a shifting tool for selectively positioning a mechanicalsliding sleeve valve in multiple operational positions. However, the waythe valve is operated implies a complex mechanism and a great number ofcomponents, thereby making necessary higher maintenance costs.

Therefore, there is a need for a system comprising a flow rateregulating device and a shifting tool for regulating the flow rate atthe bottom of an oil well, wherein said oil well has a casing with a3½-inch diameter or less, the system allowing an unlimited number ofselectivity stages and the flow rate regulation per injection zone, insecondary or tertiary recovery injection wells without the need to moveor remove the installation (set of valves, packers and tubing) from thewell and thereby avoiding intervention with pulling equipment or anotheroil rig equipment.

BRIEF DESCRIPTION OF THE INVENTION

Based on the above considerations, the present invention provides asolution to the aforementioned problems by providing an injection flowrate regulating system for slimhole wells (i.e. casing of 3½ inches orless), actuated by a shifting tool without the need to intervene thewell with oil rig equipment, for an unlimited number of zones ofinterest, the system geometrically providing an inner passage forintroducing flow rate measurement tools and being suitable forregulating flow rate of fluids including gas, water (secondary recovery)and/or polymer solutions, surfactants, alkali-surfactant-polymer (ASP),etc. in enhanced oil recovery (EOR) processes.

It should be noted that the flow rate regulation system of the inventionmay be also applied to oil wells with casing diameters greater than 3½inches.

Consequently, it is an object of the present invention a flow rateregulating system for flow rate regulation within an oil well, whereinthe well has a casing with a diameter less than or equal to 3½ inches,wherein the flow rate regulating system comprises:

-   -   a) at least one flow rate regulating valve, for regulating flow        rate, having a generally cylindrical body with a plurality of        elongated grooves or holes, a top sub in an upper portion and a        sliding sleeve within; and    -   b) a regulating and calibrating shifting tool for regulating and        calibrating the position of the sliding sleeve, which has a        generally cylindrical collet, a block set and a pair of nuts on        each side of the block set.

In a preferred embodiment of the present invention, the system comprisesa flow rate regulating valve for each well layer, without any limitationregarding the number of valves to be installed in the well.

In a preferred embodiment of the present invention, the sliding sleevehas a free inner passage that allows the shifting tool and flow ratemeasurement tools passage in order to establish a fluid distributiontherein. The obtained measures are extremely important for monitoringand tracking the reservoir.

In a preferred embodiment of the present invention, the sliding sleevehas a notch on its inner surface.

In a preferred embodiment of the present invention, the collet has aprotuberance at its lower end.

In a preferred embodiment of the present invention, the shifting tool isdesigned so as to freely pass through the interior of the at least oneflow rate regulating valve.

In a preferred embodiment of the present invention, the block set allowsgradually regulating the sliding sleeve displacement according to itsposition in relation to the collet.

In a preferred embodiment of the present invention, the pair of nutscomprises a nut and a lock nut.

In a preferred embodiment of the present invention, the shifting tool isactuated from the surface by a slickline or wireline equipment.

In this way the invention provides a selective installation system forslimhole wells. Each of the multiple injection or production zones has asliding sleeve for regulating the flow rate and a full passage formaneuvering the shifting tool next to wire or cable tools and being ableto place or actuate other regulating valves sliding sleeves that arelocated in different depths in the same well, according to thecharacteristics of the reservoir, either for producing oil or injectingwater or other fluids. The sliding sleeve also allows the passage offlow rate measurement tools in order to know the flow rate distribution,allowing in this way the monitoring of the reservoir. Likewise, there isno need of removing the installation (valves, packers and tubing)through the intervention of pulling equipment or oil rig equipment, incase it is desired to modify the regulation of any of the devices,thereby making the selective installation system economically viable.

Additionally, the flow rate regulating system of the present inventionis designed to be used both in water injection wells for secondaryrecovery systems and tertiary recovery (EOR) systems, thus the design ofthe grooves or holes through which the fluid circulates towards theformation is such that it does not cause degradation of the fluid(polymer solution, surfactant, ASP, etc.), and also the system may beused in producing wells for the regulation of hydrocarbon or water flowrate at the bottom of the well.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is a view of the longitudinal section of an embodiment of oneflow rate regulating valve according to the present invention.

FIG. 2 is a view of the longitudinal section of an embodiment of theshifting tool according to the present invention.

FIG. 3 is a view of the longitudinal section of an embodiment of theflow rate regulating system according to the present invention.

FIG. 4A is a partial view of the embodiment of the flow rate regulatingsystem shown in FIG. 3 with the regulating valve closed.

FIG. 4B is a partial view of the embodiment of the flow rate regulatingsystem shown in FIG. 3 with the valve grooves 20% uncovered of itslongitudinal section.

FIG. 4C is a partial view of the embodiment of the flow rate regulatingsystem shown in FIG. 3 with the valve grooves 60% uncovered of itslongitudinal section.

FIG. 4D is a partial view of the embodiment of the flow rate regulatingsystem shown in FIG. 3 with the valve grooves completely uncovered.

DETAILED DESCRIPTION OF THE INVENTION

The present invention will be described in further detail below, makingreference to the appended figures illustrating exemplary embodiments ofthe invention which should not be construed as limiting.

In each of the figures, same numerical references are used to indicatesame elements of the present invention.

As it is known by an expert in the corresponding technical field, in theoil industry the pipe diameter is a nominal diameter and the inner andouter pipe diameter depend on the thickness. This thickness is definedby the “poundage” of the pipe which is the weight thereof per linearmeter.

FIG. 1 shows a lateral view of the longitudinal section of an embodimentof the flow rate regulating valve 1, wherein the flow rate regulatingvalve 1 comprises a generally cylindrical body 2 that has elongatedgrooves 3 and a sliding sleeve 4 that has a plurality of seals 5 and anotch 6, and a top sub 7.

Said flow rate regulating valve 1 is positioned at the depth in which areservoir or layer is located to which it is desired to inject fluids,whether for secondary or tertiary recovery (EOR), or from which it isdesired to produce oil; and as many flow rate regulating valves 1 as thenumber of reservoirs or layers which are desired to inject to or producefrom, may be included for the same oil well.

The grooves 3 of the body 2 of the flow rate regulating valve 1 areresponsible for channeling the fluid from the inside of the flow rateregulating valve 1 to the outside of the flow rate regulating valve 1,i.e., to the annular space between the tubing and the casing, or viceversa, whether it is the case of an injection or production well,respectively. The sliding sleeve 4 is responsible for regulating theopening of said grooves 3 allowing, as desired and by means of ashifting tool as it will be seen below, whether a complete opening, soas to obtain maximum injection or production flow rates according to theoperating pressure differential; a partial blockage, by calibrating theposition of the sliding sleeve 4 so as to obtain the desired flow rate;or a complete blockage which would be equivalent to closing the flowrate regulating valve 1.

On the other hand, the flow rate regulating valve 1 has a top sub 7 thatworks as a stop for a shifting tool when actuating the sliding sleeve 4.

The sliding sleeve 4 has a plurality of hydraulic seals 5 in its upperand lower portion and has a notch 6 on its inner surface so that it canbe coupled with a shifting tool, as it will be seen below, in order tobe displaced so as to regulate the flow rate.

FIG. 2 shows a view of a longitudinal section of an embodiment of theshifting tool 10 according to the present invention, wherein theshifting tool 10 comprises a generally cylindrical collet 11 that has aprotuberance 12 in its lower end so as to couple with the sliding sleeve4, a block set 13 and nuts 14. The geometry and structure of theshifting tool, when the regulating valve is in operation, allows havinga sufficient inner diameter to introduce measurement tools so as todistribute flow rates to the layers or reservoirs.

The shifting tool 10 can be operated from the surface by means of aslickline or wireline equipment, being able to operate a flow rateregulating valve 1 that is at a certain well depth and place it in adesired position. More precisely, the shifting tool 10 can freely passthrough all sliding sleeves 4 and flow rate regulating valves 1 situatedin the same well, in order to regulate the valve of interest and obtainthe desired flow rate, either in injection or production mode.

The protuberance 12 at the lower end of the collet 11 of the shiftingtool 10 is configured so that it can be firmly coupled with notch 6 ofthe flow rate regulating valve 1 so that the sliding sleeve 4 can bedisplaced and the flow rate adjusted to the desired value.

The block set 13 is fixed in a certain position in relation to thecollet 11 by a pair of nuts 14 on each side of block set 13. Said pairof nuts 14 comprises a nut and a lock nut.

More specifically, the shifting tool 10 is used not only to open, closeor displace the position of the flow rate control or circulationdevices, but it has a millimetric calibration function, i.e. in steps upto 1 mm, of the position where it will locate the sliding sleeve 4, saidmillimetric calibration function being provided by the block set 13. Inother words, in addition to having the protuberance 12 for coupling withthe notch 6 of the sliding sleeve 4 that is to be displaced, theshifting tool 10 has a calibration mechanism which, based on itsgeometry, establishes the relative position of the sliding sleeve 4 andtherefore determines the total fluid passage area, thereby regulatingthe flow rate. The relative position of the sliding sleeve 4 determinesthe resulting flow rate. Changing the position of the sliding sleeve 4produces a change in the total passage area of the fluid from the insideof the flow rate regulating valve to the outside, or vice versa.

FIG. 3 shows a preferred embodiment of the flow rate regulating systemof the present invention, where it can be appreciated how the flow rateregulating valve 1 and the shifting tool 10 are related to each other inorder to calibrate the desired opening of the flow rate regulating valve1.

Said flow rate regulating system is applicable to casings with 3½-inchouter diameters and 2⅞-inch inner diameters, leaving the inner passagefree so that an unlimited number of sliding sleeves can be placed asrequired.

The calibration is aimed at setting the valve opening. For this purpose,it is necessary to establish spacing distances between the block set 13of the shifting tool 10 and the top sub 7 of the flow rate regulatingvalve 1.

Particularly, the calibration consists of establishing a certainposition of the block set 13 in relation to the collet 11 of theshifting tool 10 before lowering the shifting tool 10 through the well.The block set 13 can be displaced in relation to the collet 11 and fixedin another position by loosening and adjusting the nuts 14.

When the shifting tool 10 is lowered to a flow rate regulating valve 1that is to be operated in that well, by means of a slickline or wirelineequipment, the opening of the sliding sleeve 4 of the flow rateregulating valve 1 is already defined, since the block set 13 will stopat the top sub 7, and the sliding sleeve 4 will remain in a desiredposition according to the position in which the block set 13 was placedin relation to the collet 11.

This procedure must be done each time the tool is lowered into the wellto perform an opening or closing of any flow rate regulating valve 1.This operation requires that the operator in charge of the opening,regulating or closing operation be trained personnel.

The flow rate regulating valve 1 has an internal geometry speciallydesigned to provide a reference to the shifting tool 10 on the relativeposition in which the sliding sleeve 4 has to be positioned. At the sametime, the sliding sleeve 4 has an internal geometry specificallydesigned to allow the shifting tool 10 to pass in a downward directionand to be operated in an upward direction, except in the case that ithas already operated on a valve located in a deeper zone of the well.

FIGS. 4A-D show a partial view of the embodiment of the flow rateregulating system shown in FIG. 3 with different opening degrees of flowrate regulating valve 1. More precisely, FIG. 4A shows the flow rateregulating valve 1 completely closed, i.e., there will be no fluid flowfrom the tubing to the annular space between the tubing and the casing,and vice versa. FIG. 4B shows a partial opening of the grooves 3, beingsaid grooves 3 20% uncovered regarding the area corresponding to theirlongitudinal section, due to the actuation of protuberance 12 of theshifting tool 10 over the notch 6 of the sliding sleeve 4. FIG. 4C showsanother partial opening of the grooves, being the grooves, in this case,60% uncovered regarding the area corresponding to their longitudinalsection. Lastly, FIG. 4D shows a complete opening of the grooves, i.e.,said grooves are completely uncovered, thereby achieving the largestfluid passage area between the tubing and the annular space between thecasing and the tubing and allowing maximum flow rate values. All theseopening degrees are achieved by regulating the position of block set 13(not shown in FIGS. 4A-D) in relation to collet 11.

Unless otherwise defined, all technical and scientific terms used in thepresent disclosure have the same meaning as commonly understood by aperson skilled in the art to which the present invention belongs. Asused herein, the terms “comprises”, “has” and “includes” and theirconjugations, mean “including, but not limited to”.

The technical experts will recognize or be able to determine, using onlyroutine experimentation, many equivalents of the specific procedures,embodiments, claims and examples described herein. Such equivalents areconsidered to be within the scope of the present invention andencompassed by the attached claims. Thus, it should be understood thatalthough the present embodiments have been specifically described bypreferred embodiments and optional features, modifications andvariations thereof, may be conceived by those skilled in the art andthat such modifications and variations are considered within the scopeof the invention.

1. A flow rate regulating system for flow rate regulation within an oilwell with a casing with a diameter less than or equal to 3½ inches,wherein the flow rate regulating system comprises: at least one flowrate regulating valve for regulating flow rate, having a generallycylindrical body with a plurality of elongated grooves, a top sub in anupper portion and a sliding sleeve within; and a regulating andcalibrating shifting tool for regulating and calibrating the position ofthe sliding sleeve which has a generally cylindrical collet, a block setand a pair of nuts on each side of the block set.
 2. The systemaccording to claim 1, wherein the at least one flow rate regulatingvalve comprises a flow rate regulating valve for each well layer.
 3. Thesystem according to claim 1, wherein the sliding sleeve has a free innerpassage that allows the shifting tool and flow measurement tools passagein order to establish a fluid distribution therein.
 4. The systemaccording to claim 1, wherein the sliding sleeve has a notch on itsinner surface.
 5. The system according to claim 1, wherein the collethas a protuberance at its lower end.
 6. The system according to claim 1,wherein the shifting tool is designed to freely pass through theinterior of the at least one flow rate regulating valve.
 7. The systemaccording to claim 1, wherein the block set allows gradually regulatingthe displacement of the sliding sleeve according to its position inrelation to the collet.
 8. The system according to claim 1, wherein thepair of nuts comprise a nut and a lock nut.
 9. The system according toclaim 1, wherein the shifting tool is actuated from the surface by aslickline or wireline equipment